Digital overcurrent relay with voltage protection and 3×3 digit LED display TRM-30F

TRM-30F overcurrent monitoring relay with display, three-phase up to 25A

It is designed to protect equipment sensitive to operating current and voltage values against errors that may occur due to:

• current overload (adjustable current value 0.5 ... 30 A)
• current asymmetry (50%, fixed value)
• voltage asymmetry (30%, fixed value)
• overvoltage and undervoltage (Umin: 265 V, Umax: 440 V, fixed value)

The TRM-30F digital overload relay with display allows viewing the current in each phase and protects the motor or device against overcurrent, overvoltage, undervoltage, phase failure, and phase reversal. These digital overload relays are designed to prevent damage to the motor/load caused by high currents, while simultaneously monitoring the current flowing in each phase on the display. They can also check the accumulated voltage values between phases.

Thanks to the two output relays (1x NO, 1x NC), it is also possible to control or disconnect the load when a nominal overcurrent value is reached, or to connect a signaling contact to the control system. The TRM-xx digital relays have built-in current transformers and a 3x3 digit display for current indication.

Application and operating principle

1. Connect the device according to the wiring diagram. Incorrect connection may damage the device.
2. Adjust the device overcurrent through the ">A" command according to the operating current of the load to be controlled.
3. When power is turned on, the set overcurrent value appears on the upper screen and the fault waiting time on the central screen during the first second.
4. The actual phase current values are displayed after one second of operation and the indicator LED lights up.
5. When the "V/A/RESET" button is pressed, the combined voltage values between phases are displayed.

Actuators

• "A>" - setting of the allowable overload; the value is displayed on the upper screen.
• "sec." - regulation of the overcurrent fault waiting time; the value is displayed on the central screen.

Contact status

• NO 95-96, NC 97-98:

• Device powered off or in fault condition: NO open, NC closed.
• Device powered and without fault: NO open, NC open.

Indicator LED

• LED "V" - lights up in case of overvoltage/undervoltage or voltage asymmetry error.
• LED "A" - lights up in case of high current or current asymmetry error.
• "XI" LED - lights up when the phase sequence is incorrect.
• "NOR" LED - lights up when the device is powered and the system is error-free.

Function of the "V/A/RESET" button

• Reset: Pressing for 3 seconds clears the error, "A" LED turns off, NO contact closes, NC contact opens.
• V/A: A brief press switches the display between current and voltage values.

Protection and operating principle

1. Overcurrent protection (0.5-30 A):

• Fault state input: when defined overcurrent is exceeded, the defined time is waited. Phase display flashes, "A" LED is on, NO open, NC closed, NOR LED off.
• Error condition output: current below nominal value, press reset for 3 seconds.

2. Current asymmetry protection:

• Input: current difference between phases >50%, wait 3 seconds, display flashes, "A" LED on.
• Output: difference <50%, press reset for 3 seconds.

3. Overvoltage protection (U>440 V):

• Input: voltage >440 V, wait 3 seconds, display flashes, "V" LED on.
• Output: voltage <435 V for 3 seconds.

4. Undervoltage protection (U<265 V):

• Input: voltage <265 V, wait 3 seconds, display flashes, "V" LED lights up.
• Output: voltage >270 V for 3 seconds.

5. Voltage asymmetry protection:

• Input: voltage difference >30%, wait 3 seconds, display flashes, "V" LED lights up.
• Output: difference <30% for 3 seconds.

6. Phase sequence protection:

• Incorrect phase connection lights the "XI" LED.

Current asymmetry calculation

The instrument calculates asymmetry according to the formula:

Example: ((25 - 15) / 25) × 100 = 40% current asymmetry.

Technical specifications

• Supply voltage: measured voltage 3f 3x400 VAC
• Operating voltage (Un): 3x380 VAC 50/60 Hz, own power <10 VA
• Adjustable overcurrent (Overload): 0.5-30 A
• Fault delay time (t): 0-20 s
• Display: 3x3 digits, 9 mm height, 7 indicator LEDs
• Overvoltage: 440 V (L-L)
• Undervoltage: 265 V (L-L)
• Voltage asymmetry: 30%
• Current asymmetry: 50%
• Asymmetry error delay time: 3 s
• 2x output relays (1x NO, 1x NC): 3 A / 250 V AC (resistive load)
• Connection type: screw terminals
• Cable cross-section: 2.5 mm² (relay contacts) / 6 mm² (input and output loads for measurement)
• Weight: max. 380 g
• Mounting: on DIN rail
• Operating temperature: -20°C ... +55°C
• Operating altitude: <2000 m